1. Field of the Invention
The present invention relates to washing machines, and more particularly, to a washing machine having means for detecting floating laundry, such as a pillow, over a preset height, and a method for controlling the same, which enables progression of washing without spray of water or damaging the laundry even if the laundry floats.
2. Background of the Related Art
In general, the washing machine is an appliance in which various dirt stuck to clothes and beddings is removed by using softening action of detergent, friction of water circulation caused by rotation of washing blades, and impacts a pulsator applies to the laundry. An amount and kinds of the laundry may be detected by sensors; a washing process may be set automatically; washing water may be supplied to a proper level according to the amount and kinds of the laundry; and washing may occur under the control of a microcomputer.
In the meantime, a related art washing machine may be driven by transmitting a rotating power from a driving motor to a washing shaft through power transmission belt and pulleys to rotate a pulsator, or to a spinning shaft to rotate a washing and spinning tub, or by rotating the washing and spinning tub at different speeds in washing and spinning under the speed control of a brushless direct current (BLDC) motor.
Along with these, the related art washing machine may be driven by rotating only the pulsator at a low speed in washing, and rotating the pulsator and the spinning tub at a high speed and spinning simultaneously through different power transmission paths even though the BLDC motor is used. Penetration washing may be used in the related art washing machine. In penetration washing, water pumped to the washing tub is sprayed into the washing tub so that the water washes the laundry as the water penetrates through the laundry or washing blades are rotated in one direction at a high speed. FIG. 1 illustrates a section of a penetration washing machine, schematically.
Referring to FIG. 1, the related art penetration washing machine is provided with a water storage tub 2 supported on a plurality of supports 4 inside of an outer case 1, a washing tub 3 rotatably fixed to a washing shaft 6 inside of the washing tub 2 having a plurality of holes 3a in a wall for holding laundry, a pulsator 5 formed as a unit with the washing tub on an inside bottom thereof for forming water circulation, and a motor 7 under the water storage tub 2 on one side thereof for rotating the washing tub 3.
There are a tub cover 8 on a top of the water storage tub 2 for introducing the washing water rising through a gap between the washing tub 3 and the water storage tub into an inside of the washing tub, a water supply pipe 10 at one side of rear of the outer case 1 connected to an exterior for supplying the washing water to the washing tub 3, and a drain pipe 11 at one side of lower side of the water storage tub 2 for draining the washing water discharged through the holes 3a in the washing tub to an exterior finally.
There are a detergent box 12 on the water supply pipe 10 at one side of top of the washing tub 3 for automatic introduction of detergent by means of the washing water, and a balance weighter along a circumference of a top end of the washing tub 3 for prevention of vibration of the washing tub while it is spinning.
The penetration washing machine accomplishes a washing cycle by rotating the washing tub 3 and the pulsator 5 at a high speed in one direction. In detail, the laundry comes to make close contact with the inside surface of the washing tub as the washing tub 3 and the pulsator 5 rotate in one direction at a high speed. Washing water moving through the pass through holes 3a in the washing tub is re-introduced to the inside of the washing tub 3 again through the tub cover 8 and penetrates the laundry, to separate dirt from the laundry as this process is repeated.
Meanwhile, different from the foregoing system, there may be a system in which the pulsator 5, forming water circulation, is not formed as one unit with the washing tub 5, but formed separately.
That is, the washing tub 3 and the pulsator 5 are separate so that the direction of rotation of the washing tub 3 and the pulsator 5 are opposite in washing as the washing tub 3 rotates. In addition to this, there is a washing machine (see FIG. 2E) having a circulative water supply system in which water inside of the washing tub 3 is pumped to the inside of the washing tub 3 again by a pump P.
However, the foregoing different type of related art washing machines have the following problems in washing.
None of the related art washing machines is able to detect floating laundry, such as a pillow, and non performs a proper algorithm for coping with the floating laundry, which causes the following problems.
Referring to FIG. 2A, when laundry, such as a pillow, floats in an upper part of the washing tub 3, the floating laundry obstructs the water supply path, such that the water supply fails, or the water supplied to the washing machine splashes from the pillow to a space between the water storage tub 2 and the outer case 1.
Particularly, floating laundry causes problems for the different water supply methods including a first method in which the water is supplied when the washing tub 3 is stationary, a second method in which the water is supplied while the washing tub 3 is rotated, and a third method in combination of above two methods. If the laundry floats in the first method, the water supply passage is blocked if a water supply pressure is low or the water is splashed in all directions because it hits the floating laundry if the water supply pressure is high. If the laundry floats in the second method, the water is splashed in all directions from rotating laundry regardless of water supply pressure.
Next, referring to FIG. 2B, if the laundry floats higher than the washing tub 3 in a penetration washing, the washing water collides onto the floated laundry, and splashes in all direction therefrom, the washing water penetrates through the laundry, escapes through the holes 3a, and is introduced into the inside of the washing tub 3 again through the tub cover 8, to cause the washing water to enter into the space between the water storage tub 2 and the outer case 1.
Referring to FIG. 2C, in shower rinsing when the water is supplied while the water storage tub 2 is rotated, if the laundry floats higher than the washing tub 3, the water supplied for the shower rinsing is splashed from the laundry, to cause the water to enter into a space between the water storage tub 2 and the outer case 1, together with detergent.
Referring to FIG. 2D, if the washing tub 3 rotates at a high speed when the laundry, such as a pillow, floats higher than the washing tub 3, and may become in close contact to an inside circumferential surface of the tub cover 8 during spinning, causing damage to the laundry or causing the inside circumferential surface of the tub cover 8 to wear down.
Referring to FIG. 2E, in a pumping circulation method in which the washing water is pumped from the washing tub 3, to spray the washing water into the washing tub 3 through the water supply hole 40, or from a side of the washing tub 3, and the water storage tub 2 is rotated while the washing water is supplied in the shower ringing. If the laundry floats higher than the washing tub 3, the re-supplying water into the washing tub 3 after circulation is splashed from the laundry, to cause the washing water to enter into the gap between the water storage tub 3 and the outer case 1, together with the detergent.
In the meantime, when the washing water splashes from the floating laundry and enters into the gap between the water storage tub 2 and the outer case 1, the water infiltrates into an insulated part, to cause a safety problem, such as short circuit, or the like, or damages carpet when one is on the floor.
When the water splash caused by the floating laundry is intensive in the water supply, the water level cannot reach to a preset level, to require a long water supply time, which results in waste of water.
If the washing water is splashed to outside of the water storage tub 2 in the penetration washing, or in the circulative washing, other than the water supply, shortage of the washing water is caused to require re-supply of washing water.
In summary, since none of the related art washing machine and related art washing methods are able to detect floating laundry, and they fail to suggests a washing method for coping with the problem properly, there may be deterioration of washing performance and damage to the laundry caused by the shortage of water, to result in safety problems and waste of water.